We know that a symmetrical face defines physical beauty. We know that women observe men’s shoes as a means of analysis. White teeth are a big factor in making a positive first impression.
All the research states that the impact of people speaking is predominantly their physical state then the voice and then the actual words are minimal. Which is primarily because we have lost our ability to listen with the advent of television.
Most information was relayed by story telling until the invention of writing which is still a relatively new concept in our evolution.
Your mental and physical preparation is critical before you speak. I like to go for a run to relax and go over the script in my head while running. We need to look relaxed when speaking but everyone has their own balance between being relaxed but also enthused by what they are talking about. We respond to energy primarily.
When need to really think about and practice what we are going to talk about and pass it by someone else to get their input. So often people just go through the motions to get it over with rather than making it an opportunity to impress when speaking. An opportunity to impart your beliefs so that people can think about their beliefs and behaviour. To not try and speak thinking what the audience wants to hear rather than saying what you want to say. As long as you are not trying to be reactive or aggressive as we respond to assertion not aggression or passiveness.
Camus the French writer stated to “Know oneself you need to assert yourself.”
When speaking your objective is always to engage your audience. Remembering that you need to be clear about what you want the audience to hear and that you stimulate the audience to want to listen to you. That needs practise as it changes each time as your experience changes and that each audience is different.